Plant physiological responses to hydrologically mediated changes in nitrogen supply on a boreal forest floodplain: a mechanism explaining the discrepancy in nitrogen demand and supply
Plant physiological responses to hydrologically mediated changes in nitrogen supply on a boreal forest floodplain: a mechanism explaining the discrepancy in nitrogen demand and supply
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DOI：
10.1007/s11104-010-0676-8
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发表时间：
2011-05
期刊：
影响因子：
4.9
通讯作者：
L. Koyama;K. Kielland
中科院分区：
文献类型：
--
作者：
L. Koyama;K. Kielland
在阿拉斯加内陆河岸植被演替的早期阶段，植物对氮的需求和土壤对氮的供应存在差异。我们假设，水文介导的氮供应作为一种机制，以平衡这种明显的植物氮供应不足。为了验证这一假设，我们进行了示踪实验，并测量了硝酸还原酶（NRA）在阿拉斯加内陆的塔纳纳河的早期演替洪泛区在夏季的活动。同位素数据表明，河流/地下水是植物水分的重要来源，潜流N可以被早期演替物种吸收。植物NRA一般随着生长季节的进展而增加，NO3−-N的可用性增加。沙柳和香杨使用的NO3−-N，以及植物NRA相对于河流排放化学和土壤NO3−-N浓度的时间，强烈表明植物对NO3−-N的吸收与河流动力学有关。此外，这种生理功能有助于解释氮矿化和生产力之间的明显差异，在这些河岸生态系统，并表明，植物氮的可用性在这些河岸的立场是根据显着的水文控制。
A discrepancy between plant demand and soil supply of nitrogen (N) has been observed in early successional stages of riparian vegetation in interior Alaska. We hypothesized that a hydrologically mediated N supply serves as a mechanism to balance this apparent deficiency of plant N supply. To test this hypothesis, we conducted a tracer experiment and measured the activity of nitrate reductase (NRA) over the summer on the early successional floodplain of the Tanana River in interior Alaska. Isotopic data showed that river-/groundwater was an important source of plant water and that hyporheic N could be absorbed by early successional species. Plant NRA generally increased as the growing season progressed, and NO3−-N availability increased. BothSalix interiorRowlee andPopulus balsamiferaL. used NO3−-N, and the timing of plant NRA relative to river discharge chemistry and soil NO3−-N concentrations, strongly suggest that plant uptake of NO3−-N is coupled to fluvial dynamics. Moreover, this physiological function helps explain the apparent discrepancy between N mineralization and productivity in these riparian ecosystems, and demonstrates that plant N availability in these riparian stands is under significant hydrological control.